And the region’s demand for electricity rules out closing the plant, Duke District Manager Jason Walls said following the federal government’s announcement that it would further restrict emissions from coal-fired power plants.

The U.S Environmental Protection Agency plan calls for the nation’s power plants to cut carbon emissions by more than a third by 2030. North Carolina’s assigned target would require reductions of nearly 40 percent.

The plan is expected to hasten the country’s shift from coal toward natural gas, energy efficiency and renewable sources such as wind and solar.

Lake Julian uses cleaner-burning natural gas, but pipelines that carry the fuel into the region aren’t big enough to handle what would be needed to forgo burning coal, Walls said.

Duke Energy in responding to the regulations pointed out that it has already shuttered seven older coal-fired plants and reduced carbon emissions by 20 percent since 2005.

The Asheville area also gets electricity through the grid from other regions, but the flow isn’t sufficient to outset the power provided by burning coal, Walls said.

Julie Mayfield, co-director of the Asheville-based environmental group Western North Carolina Alliance, said she understands the plant can’t be closed anytime soon.

“I’ve heard (Duke) say they can’t close the Asheville plant until they have a replacement for that energy in this region,” she said. “That makes perfect sense. We don’t want people to be in the dark either.”

But Mayfield noted that the new carbon regulations are years away from being fully implemented. She hopes that eventually the burning of coal here will be replaced by other sources and reduced demand.

Drew Elliot, a spokesman for the N.C. Department of Environment and Natural Resources was critical of the EPA plan, saying it would lead to lawsuits and higher electricity rates that could hurt job growth.

Mayfield said the plan for reducing carbon emissions is a step in the right direction.

“Thirty percent by 2030 is nothing to sneeze at,” she said. “It’s certainly not as aggressive as it could be”

Duke is in the process of reviewing the 645-page plan, spokesman Chad Eaton said.

“It’s too soon to tell what impact EPA’s proposed rule will have on our operations,” he said. “There’s a 120-day comment period. We will file comments and we will be part of the rulemaking process.”

The Asheville plant burns about 700,000 tons of coal each year, enough to fill about 6,300 rail cars, Walls said.

The state General Assembly enacted the Clean Smokestacks Act in 2002, requiring utilities to install modern pollution control equipment on their plants.

The Asheville plant was among the first to be outfitted with scrubbers, which resulted in a 96 percent reduction in sulfur dioxide emissions and an 85 percent cut in nitrogen oxides emissions, Walls said. More than $300 million has been invested in upgrading the plant.

The plant emitted 1.5 million tons of carbon dioxide in 2013, which he said is about half what was emitted in 2000. But Walls said the reduction had nothing to do with the new pollution control technology.

“The reduction in carbon is attributable simply to using less coal to generate electricity,” he said.

The plant has been able to reduce coal consumption by increasing its use of natural gas as supplies have become cheaper and more plentiful in recent years, he said.

But because the primary use for natural gas when it’s cold in Western North Carolina is for heating, there isn’t enough left for generating much power at the plant in the winter, Walls said.

Walls said the demand for electricity in the region has more than doubled since 1975. He attributes the rise to population growth, more home appliances and increased use of air conditioning.

The plant, which began operating in 1964, serves 164,000 customers in 10 counties.